Withanolides from the stem bark of Withania somnifera

Phytochemical studies on the stem bark of Withania somnifera, collected from the southern region of New Delhi, resulted in the isolation of five new withanolides, namely withasomnilide, withasomniferanolide, somniferanolide, somniferawithanolide and somniwithanolide. Their structures have been established as (20R, 22R)-1-oxo-5 alpha, 8 beta-dihydroxywitha-6 alpha, 7 beta-epoxide-2,24-dienolide, (20R, 22R)-1-oxo-8 beta, 11 beta, 16 beta-trihydroxywitha-2,5,24-trienolide, (20R, 22R)-1-oxo-8 beta, 11 beta-dihydroxywitha-16 alpha, 17 alpha-epoxy-2,5,24-trienolide, (20R, 22R)-1-oxo-8 beta,18,20 beta-trihydroxywitha-2,5,24-trienolide and (20R, 22R)-1-oxo-7 beta, 18,20 beta,27-tetrahydroxywitha-2,4,24-trienolide, respectively, on the basis of spectroscopic techniques and chemical means. Copyright(C) 1997 Elsevier Science Ltd.